European foreign ministers agreed to extend the embargo for three months, but will amend it to enable "greater non-lethal support and technical assistance" to protect civilians.

Foreign Secretary William Hague said the agreement would allow the United Kingdom to "provide assistance we have been restricted in giving before".

The UK was pushing for the embargo to be eased and Mr Hague claimed the decision was "an important and welcome step forward".

He said: "It shows we can change the arms embargo, and the worse the situation becomes the more ready we will be to change it: the embargo will be reviewed again in three months. This step establishes an extremely important precedent, and is an important step in itself. It will allow us now to supply a greater range of equipment to help to protect civilian life in Syria. It will also enable us to give assistance that we've been restricted in giving before."

A United Nations commission has found that fighters on both sides in Syria's civil war have committed atrocities and should be brought to justice. Mr Hague said the report painted a "devastating picture of human rights abuses and suffering".

The Commission of Inquiry's report accused both sides of atrocities but found that those committed by rebel fighters had not reached the "intensity and scale" of those committed by Bashar Assad's forces.

Mr Hague said: "The report by the UN Commission of Inquiry on Syria paints a devastating picture of human rights abuses and suffering. Our thoughts are with all the Syrian people who continue to endure this terrible situation.

"The Commission's report confirms that the Assad regime bears overwhelming responsibility for the situation in Syria, and for the worst human rights violations and abuses. We therefore welcome the Commission's call for the UN Security Council to refer Syria to the International Criminal Court, a course of action that we strongly support.

"We will remain at the forefront of international efforts to ensure accountability for the crimes being committed in Syria, and will continue to support the work of UN Commission of Inquiry. The UK condemns in the strongest possible terms all human rights violations and abuses in Syria. We call on all sides to respect international humanitarian and human rights laws, and to pursue a genuine Syrian-led political transition."